Is it possible, that this was the only Last Battle that there ever was? I only suggest this for a couple of reasons. One, the dark one exists outside of time, and so when Rand stepped outside the pattern he was outside of time itself. Wouldn't this mean that there would be an infinite number of Dragons there too? Unless it only happened once? This could be explained by the time warping around the bore. This warping would also account for all of the varied realities that Perrin saw when he killed slayer. At the time he was very close to the Bore and reality would have been very thin. Therefore, at a critical moment like killing his nemesis, he saw all of the realities that were centered in time around the single moment of the Dragon sealing the bore. What I am suggesting is that the pattern loops itself back to the same event, the sealing of the bore, with occurs an infinite number of times throughout the pattern, but really only once. A time line would look like a rose on a polar graph with an infinite number of petals, and the sealing of the bore existing at the center. So everything except for the actual conflict would occur differently, like the battle that Matt lead, but it would become more and more similar until as you approached the Bore, until you reached Rand. There it would have warped enough for it to be the exact same event. I don't know if I buy this but it is a thought worth considering.